The present invention relates to the manufacture of storage batteries and more particularly, to a method of assembling banks of battery electrodes.
The method can be utilized for making any types of batteries, since it ensures the automatic assembly of a preset number of electrodes of opposite polarity with separators into a pack of a desired thickness. A device for practicing said method can be utilized both separately and as part of an automatic battery assembly line.
The method according to the present invention will be used to the best advantage in the manufacture of nickel-cadmium batteries of a high power capacity made up of extra-thin low-stiffness electrodes, used in aviation, battery-powered trucks, etc.
The problem of automating the assembly of electrode banks of powerful batteries consists in that the bank of electrodes should be inserted into the container with a certain preset tightness of fit. The existing methods of electrode manufacture fail to guarantee the requisite accuracy of electrode thickness which is required for obtaining the necessary thickness of the assembled bank.
In many cases, more stringent demands on the tolerances for electrode thickness are either impossible from the technical point of view, or economically impracticable.
Therefore, the electrode banks of such batteries are assembled mostly by hand; in this process the electrodes of the required thickness are selected at the end of the assembly operation so as to ensure the required thickness of the bank containing a preset number of electrodes.
Known in the prior art is a method of mechanized assembly of electrode banks consisting in that a lever-and-cam manipulator with a grip reciprocates above a conveyor and feeders, picks up alternately the negative and positive electrodes from the feeders and places them one on top of another into a pile on the conveyor which moves periodically step-by-step between the adjacent feeders.
In this method, a plurality of feeders and manipulators are installed near one conveyor (the number of said feeders and manipulators corresponding to the number of electrodes and separators in a battery).
This method cannot ensure high efficiency since the manipulator reciprocates with an idle stroke each time when placing an electrode into a pile. In case of selective assembly of a large number of thin electrodes into banks (30 to 70 electrodes per bank), the assembly device will be bulky and difficult to operate. The method of assembling the banks in this device with a group of feeders installed on both sides of the conveyor and a twinned manipulator operating without idle strokes cannot be utilized for selective assembly, since in this case it is impossible to install electrodes of different thickness groups so as to ensure the required thickness of the bank.
Also known in the prior art is a method of mechanized assembly by loading electrodes of opposite polarity and separators into the feeders arranged above a conveyor with carriages, releasing one electrode from underneath each feeder, assembling a pile of electrodes and separators during the step-by-step movement of the conveyor carriages and assembling a bank of electrode from several piles removed from the carriage by a pack-gathering mechanism after which the bank is withdrawn from the zone of assembly.
This method likewise fails to produce a bank of a predetermined thickness when the thickness of individual electrodes varies within wide limits. Besides, this method is not suitable for assembling banks from thin electrodes since the feeders release the electrodes from the bottom of the pile and cannot work reliably unless the electrodes are sufficiently thick and strong.
The prior art device for assembling a bank of battery electrodes according to the method described above comprises a plurality of feeders (carrying devices) for individual piles of electrodes and separators, located near the assembly zones and made in the form of a conveying device moving intermittently along the row of feeders. Installed along-side of the row of grips (suction cups) for picking the upper plates and separators and transferring them to the assembly zones is a lever-and-cam manipulator which is linked with a common driving camshaft.
The device can also be made with the feeders arranged in a circle on a table which moves intermittently between the feeders in which case the grips actuated by the lever-and-cam manipulator will pick up alternately the plates or separators from each feeder and place them in a pile on the conveyor. In this case, the conveyor will make each step after the complete assembly of the electrode bank due to a kinematic linkage between the conveyor drive and the number of working cycles of the manipulator.
There is also another version of the device with the feeders arranged on both sides of the conveyor and with a pair of grips located above the feeders at such a distance from each other that within a working cycle they pick the plates alternately from the opposite (relative to the conveyor) feeders and simultaneously place the preceding plate into a pile on the conveyor. In this case, the manipulator places two plates within a working stroke, i.e. it works without idle motions. Here the feeders are installed in pairs opposite each other on both sides of the conveyor and each pair of feeders executes shuttle motions relative to the line of movement of the manipulator with two grips arranged perpendicularly to the location of the conveyor which allows the number of manipulators to be reduced by 50% but having the same output.
In these cases, there is also a time dependence of the intermittent advancement of the conveyor on the number of working strokes of the manipulator required for gathering the necessary number of plates and separators into a bank.
The above-described device for assembling banks of battery electrodes has serious disadvantages which prevent it from being employed for the selective assembly of banks containing a large number of electrodes (30 to 70) and having a predetermined thickness.
For example, if the device is intended to perform the selective assembly of a bank of twenty nine electrodes, it has to comprise at least twenty nine feeders and manipulators. Such a large, complicated and cumbersome device will fail to yield sufficient output due to a large number of idle strokes executed by the cam-and-lever mechanisms during assembly. The versions of the device covered by the patent and described above in which the idle strokes of the manipulators are eliminated, cannot be used for selective assembly at all because in these cases there is no possibility whatsoever of installing groups of electrodes of different thickness, sorted out in advance.
Besides, refitting of the above-cited device for assembling the banks of different type-sizes is difficult since the operation of the feeders and assembly manipulators has a definite relation to a certain type-size of the bank of electrodes so that refitting will involve labor-consuming replacement of the working elements followed by the adjustment of the entire mechanism.